Infanticide and Male-Female 'Friendships' in Savanna Baboons

这个项目解决了关于灵长类生物学的两个基本问题。首先，为什么成年男性和女性拥有持久的纽带？在大多数哺乳动物物种中，两性在雌性发情期或生育期前后相互作用；在此之后，雄性和雌性通常追求基本上不同的生活。然而，在灵长类动物中，雄性和不能生育(无性繁殖)的雌性之间的永久联系不仅比哺乳动物更常见，这在几乎所有的猴子和类人猿中都是规则。然而，灵长类动物中雌雄关系普遍和多变的进化原因仍不清楚。其次，为什么杀婴是一些男性的生殖策略，而不是其他男性的生殖策略？杀婴，杀死被抚养的婴儿(通常是男性)，在哺乳动物中广泛存在，但表达方式各不相同。这两个看似不相关的问题在一个新的理论中结合在一起，该理论提出，男性和女性彼此之间形成社会关系，以保护幼崽不受杀婴之害。研究人员将通过对两种关系密切、既有相似之处又有重要差异的稀树大草原狒狒的研究来验证这一假设。肯尼亚的橄榄狒狒(Papio Cynocephalus Anubis)和博茨瓦纳的Chacma Baboons(P.cynocephalus ursinus)都生活在由多个雄性、多个雌性组成的大型群体中，在这些群体中，哺乳期的雌性与特定的雄性保持着密切的联系--俗称“友谊”。然而，雄性杀婴在查克玛狒狒中很常见，但在橄榄狒狒中很少见。通过对这两个种群的比较研究，研究人员将回答以下问题：(1)雄性如何从友谊行为中受益：雄性是朋友的婴儿的遗传父亲，还是像橄榄狒狒所说的那样，他们照顾没有血缘关系的婴儿，因为母亲会选择他们作为未来后代的父亲？(2)雌性如何从与雄性的友谊中受益：它们是否在Chacma Baboons中获得了雄性抗杀婴保护，以及在不那么杀婴的橄榄狒狒中获得了一些其他好处(例如，不受雄性骚扰)？(3)雄性和雌性之间的联系是否会因雄性对雌性婴儿的亲子关系以及雌性从两个种群的友谊中获得的不同好处而有所不同？(4)杀婴是否会增加雄性Chacma狒狒的繁殖成功？(5)为什么一些(但不是所有)雄性Chacma狒狒在达到统治等级的阿尔法状态时会变得杀婴，而雄性橄榄狒狒却很少这样做？最终，对非人类灵长类动物的研究可能会提高我们对我们自己物种内性别之间社会关系的理解。

This project addresses two fundamental questions about primate biology. First, why do adult males and females share enduring bonds? In the majority of mammalian species, the sexes interact affiliatively around the period of female estrus or fertility; after that, males and females typically pursue largely separate lives. In primates, however, permanent association between males and nonfertile (anestrous) females is not only more common than in mammals generally, it is the rule in virtually all monkeys and apes. The evolutionary reasons for the ubiquity and variability of female-male relations in primates remain unknown, however. Second, why is infanticide a reproductive strategy of some males, but not others? Infanticide, the killing of dependent infants (usually by males), is widespread but variably expressed in mammals. These two apparently unrelated questions are united in a new theory that proposes that males and females form social relationships with one another in order to protect young against infanticide. The researchers will test this hypothesis in a study of two closely related savanna baboons that share similarities as well as important differences. The olive baboons (Papio cynocephalus anubis) of Kenya and the chacma baboons (P. cynocephalus ursinus) of Botswana both live in large, multi-male, multi-female groups in which lactating females maintain close bonds with particular males--popularly known as "friendships". Infanticide by males, however, is common in chacma baboons, but rare in olives baboons. By comparatively studying both populations, the researchers will answer the following questions: (1) how do males benefit from friendship behavior: are males the genetic fathers of their friends' infants, or, as argued for olive baboons, do they care for unrelated infants because mothers will then choose them as sires of future offspring?; (2) how do females benefit from friendships with males: do they obtain male anti-infanticide protection in chacma baboons, and some other benefit (such as protection from male harassment directed at females) in the less infanticidal olive baboon?; (3) do bonds between males and females vary in light of the male's paternity of the female's infant and due to the different benefits females may derive from friendships in the two populations? (4) does infanticide increase the reproductive success of male chacma baboons?; (5) why do some (but not all) male chacma baboons become infanticidal when reaching alpha status in the dominance hierarchy, whereas few male olive baboons ever do? Ultimately, the study of a nonhuman primate may improve our understanding of social relationships between the sexes within our own species.